2006 Front caliper mounting bolts

[Oso]

While rebuilding my front end (see setting sag and preload thread) I managed to break the head of the top mounting bolt of the left caliper. This is when I first noticed the bolt is hollow. Is there a reason for this and should I be concerned about replacing it with one that is not hollow?

Thanks

 

[ionbeam]

Hollow bolts have been discussed in the past. Less filling, tastes great type discussion. The leading contenders are 1. heat dissipation 2. reduces unsprung weight and I'll add 3. to boggle the little minds of FJR owners, some engineer at Yamaha is having a good laugh at us

Hollow Bolts

Hollow Bolts

Hollow Bolts

 

[FJReady]

I'm postulating that the bolt is hollow to reduce unsprung weight. Probably not that important on this bike but Yamaha likes to use common parts across their fleet and I'm guessing that this is used on many Yamaha models including the sportier ones where weight is a bigger factor.

I wouldn't hesitate to use a solid bolt in its place provided that it is of comparable strength. I expect this is a high strength bolt, at least 10.9 grade.

If it can take the specified assembly torque, it is probably OK. Speaking of torque, how did you break the OEM bolt? Tightening or loosening? If it was tightening you may want to check your torque wrench. I've had my gen 1 caliper off and on at least a dozen times. No trouble breaking the bolts. Those are pretty beefy (very important too) fasteners. Something was screwy if you broke them. Determine root cause before you finish the reassembly.

 

[Intech]

What Fred said..only supposed to be 27 ft/lbs of torque. You can easily go way past that with a 3/8" ratchet. Don't want to over tighten them.

 

[Oso]

Yeah, I was tightening with a 3/8 ratchet before going to the torque wrench. I must have torqued past 27 ft/lbs because when I put the torque wrench on it broke immediately.

 

[Fred W]

They are hollow to make it easier to put the easy out into after you snapped the mother off.

For the cost of the Yamaha bolts, I'd just put one of those back in. But that's just me.

 

[Hotboot]

They are designed to stretch upon application, in high heat areas supposedly keeping torque specs consistent.

I bought new ones as the heads and threads wear out during many tire changes.

Buy new ones, use blue loc-tite as thread preservative and never a torque wrench. They should reverse drill out easily unless you deformed the threads.

 

[Fred W]

Even though these bolts are hollow, I do not believe that they reach the stretch point considering they are only supposed to be torqued to 29 ft lb. If you over torque them you may actually be stretching them, but that is not a good thing to do if it wasn't designed to be that tight.

The FSM doesn't call for loctite to be used on these bolts. It does call for a torque wrench to be used. If you never use a torque wrench you will probably never tighten them to the correct 29 ft lb.

At 29 ft lb dry torque the bolts will not loosen, and there is no need to "preserve" the threads when you only tighten them to the specified torque. Of course, if you were to use loctite, then the torque spec goes out the window.

I know there are many here that can't seem to (or don't want to) master using a torque wrench. It really isn't all the difficult. A properly functioning torque wrench used correctly with an appropriate torque spec will never cause good threads to strip out.

You can all choose to do whatever you want to your own bikes, but giving advice like that to other people is somewhat irresponsible.

 

[Constant Mesh]

I use the torque wrench on the caliper bolts. They always remove very easily for tire changes, etc.

I've never experienced a loose caliper bolt. Threadlocker is not required here.

I use the torque wrench on the fork/axle pinch bolt as well.

 

[lnewlf]

cheap enough

https://www.cheapcycleparts.com/oemparts/a/yam/5004775df8700209bc79843b/front-brake-caliper

put a standard [metric] bolt in until you can order one...

 

[Oso]

I found a metric replacement. The head is larger but it works. I'll order a few spare OEM ones in the meantime.

Thanjs.

 

[TownsendsFJR1300]

My educated guess is those bolts are designed like that so they break off if over torqued (thus saving the caliper.).

I'd be replacing with the factory bolts...

 

[Constant Mesh]

Same bolt was used through the 2010 model.

New bolt used on 2011 through today.

The price is a bit higher for the 2011 bolt.

Is it also hollow?